Immobilization of Lipase on Metal Organic Frameworks for Biodiesel Production

A comprehensive study on lipase immobilization on ZIF-67, ZIF-8 and HKUST-1 and their use in biodiesel production was performed. Highest adsorption capacity of 26.9 mg/g was achieved using ZIF-67 at 45oC and initial protein concentration of 0.6 mg/mL. Adsorption equilibrium data suggested that lipase adsorbed physically on ZIF-67 and ZIF-8 and chemically of HKUST-1. The data were best fitted with Langmuir isotherm model for the three supports. Whereas, adsorption kinetics data were best fitted using Elovish’s model for ZIF-67 and ZIF-8, and pseudo second model for HKUST-1. It was also found that the process was influenced by intraparticle and film diffusion. The prepared bio-catalyst was successfully used to catalyze biodiesel production in solvent-free medium. The ZIF-8 and ZIF-67 showed better catalytic activity achieving 88% and 90% conversion, whereas HKUST-1 showed better operational stability owing to the stronger chemical adoption. In addition, diffusion-reaction kinetics of biodiesel production using adsorbed lipase on ZIF-8 has been analysed. The investigation provided an insight into adsorption pathways and probable mechanism involved and a better understanding of their application in biodiesel production.